Method of welding metal parts



F. EARLE May 21, 1935.

.METHOD OF WELDING METAL PARTS Filed Feb. ll, 1935 INVENTOR Fran c Z6 15 arle BY ATTORNEY Patented May 21, 1935 UNITED STATES 2.00am METHOD 01 wamme ME'rAL mars Francis Earle, Montclair, N. 1., assignor to Metal & Thermit Corporation, Carteret, N. J a corporation of New Jersey Application February 11, 1933, Serial No. 656,231 2 Claims. (01.22-206) The invention relates to certain improvements in the art of welding metal parts by means of superheated molten metal and more particularly molten steel produced by alumino-thermic reaction, and to certain improvements in molds employed for such welding. An object of the invention is ,toemploy a mold having one or more risers opening into the mold cavity and a pouring gate discharging into the lowerpart of the mold space and having its inlet en'dat a higher level than the tops of the riser or risers, so that w slag accumulating in the gate will establish a static head effective to cause the metal teemed,

into the mold to completely fill the latter and enter the risers, without danger of any'of the slag entering the mold cavity to impair the weld. The invention is exemplified in j old for welding together the ends of railway rails, in the accompanying drawing, which is a transverse sectional elevation of a two part mold.

Referring to the drawing, I and 2 indicate coordinate sections of a mold adapted to enclose the ends of the railway rails, each mold section being formed oi refractory molding material rammed over suitable patterns'to form sections of the mold cavity 3, risers 4 and 5 which communicate with the moldcavity on opposite sides of the rail heads, and the sections 6 and 1 of the mold in contact with the tops of the rails defining the bottom of a basin 8. Formed in one of the mold sections, such as 2, is a pouring gate l0, which extends to and is connected with the lower part of the mold cavity and is provided with a lateral branch II, which connects with an intermediate portion of the mold cavity, Preferably just below the rail heads. As indicated, the wall l2 between the pourin ate and the basin terminates a slight distance below the top of the mold, but at some distance above the tops oi the risers 4 and 5. This construction provides a pouringgate, with its inlet end materially above the tops of the risers, so that, when the products of alumino-thermic reaction are teemed into the pouring gate, the superheated molten steel, indicated by the heavy broken lines as at 'a, will flow down the gate and first enter the lower part of the moldcavity 3, gradually rising in the latter until itreaches the level or the cross channel H, after which the molten steel will be directed along said channel ll into the mold cavity and into contact-with the head sections of the rails without material loss of heat.

When an accurately gauged charge of aluminothermic material is employed to effect the weldr enough molten steel will be produced to completely fill the mold cavity 3 and the risers 4 and 5, the body of molten metal in the risers serving to compensate for the shrinkage of the metal on cooling. Following the molten steel, the slag, indicated by the light broken lines as at b,- which is also superheated and highly fluid, will enter the pouring gate and establish'a static head, which will be efiective in forcing the molten steel to completely fill the mold cavity and the risers 4 and 5. Inasmuch as the alumino-thermic reaction. produces substantially equal proportions oi metal and slag, there will be more than enough slag to fill the pouring gate and the surplus slag, indicated at b, will overflow the top of the wall t2 into the basin 8.

Various modifications of the mold, which will accomplish the same result, have been made without departing from the invention and, obviously, molds involving the invention may be employed for welding other metal parts than railway rails. For example, the mold sections, such as I and 2, may be formed to extend only a slight distance above the top of the mold cavity, sufiicient to provide an upper wall and to accommodate one or more risers adapted to contain sufficient metal to compensate for shrinkage of the weld on cooling. With such an arrangement, the necessary elevation of the inlet end of the pouring gate may be efiected by extending thepouring gate in the form of a tube of metal or refractory material mounted on the top of the mold in alignment with theportion of the pouring gate formed in the mold proper, the tube being of such length that its top is well above the upper level of the risers, so that the molten slag accumulating in the tube will furnish the static head as v and for the purpose as hereinbefore described.

In the usual design of molds for welding, espeof the raiL thereby first filling the lower portions of the mold and rising up about and between the rail ends progressively until the entire mold space was filled; Risers were usually provided in the top of the mold adjacent the rail heads or the upper portions of other parts to be welded to insure the filling of the mold cavity with the molten metal and to compensate for shrinkage of the welded joint on cooling. It was soon found that this mode or delivering the molten metalto the mold was decidedlydisadvantageous and objectionable, as the superheated molten metal first entering the mold space or cavity and coming into contact with the lower portions of the parts to be welded would quickly give up its superheat and this partly cooled metal would then rise in the mold arid, when, it finally came to rest in the upper part of the mold, it would be cooled to such an extent as to render it ineffective to heat the upper portions of the parts to be welded to welding temperature.

Improvements were made later in which the molten metal was teemed into the pouring gate located immediately above the space between the ends of the rails or other parts to be welded and fell directly through the mold cavity into the lower portion thereof and rose gradually in the cavity until the latter was filled. By this means, there was little .or no loss 01 the superheat in the molten metal until the latter came in contact with the rail ends at its ultimate position of rest. Various other dispositions and forms of pouring gates were devised for the same general purpose, namely, to insure uniform welds brought about by direct contact of the superheated molten steel with the rail ends without any preliminary loss of the superheat.

The present invention accomplishes the same result without involving the inherent disadvantages of the old typesof molds and furthermore insures the production of homogeneous, uniform welds with a material saving of the welding material, namely, the superheated molten metal. In a mold constructed and employed in accordance with the present invention, the first portion of the superheated molten metal is directed through the pouring gate into the bottom of the mold cavity and gradually rises therein until it reaches the level of the cross channel I]. Even if there is any slight loss of the superheat in the metal filling the lower part of the mold, this loss will be compensated by the molten metal which enters the mold cavity through the cross channel ll, so

that the upper parts of the elements to be welded will be eifectively heated to welding temperature. Furthermore, it will be noted that the slag delivered to the pouring gate, after the steel has entirelyrun out of the crucible in which the reaction has been effected, will rest on top of the steel in the gate and, by its weight, depress the level of this steel, so that, when the body of steel has filled the mold cavity and found its level in the risers, a considerable saving of steel, which would ordinarily be required'to fill the pouring gate, would result. As stated, the distance of the inlet of the pouring gate above the top level of the risers may be regulated to provide any desired static head produced by the body of slag entering the pouring gate, provided such static head is not sufficient to force the slag down to the level of the cross channel II, which would permit the slag to enter the mold cavity. and come in contact with the metal parts to be welded with a consequent impairment of the weld. Under ordinary conditions, the height of the riser is so limited as to provide just sufiicient metal to compensate for contraction of the metal of the weld on cooling and the depression of the molten metal in the pouring gate by the superposed slag, together with the restriction of the dimensions of the risers, will insure the saving of considerable metal without in any way impairing the welded joint.

Another decided advantage of this type 01 mold is that any surging of the metal and of the slag following the same is almost completely eliminated. This surging in the older types of molds frequently permitted the slag to enter the mold cavity and coat the parts to be welded, thereby seriously impairing the weld, but any surging of the slag which might occur in the present type of mold would take place in the upper portion of the pouring gate and would not be sufiicient to force the slag to the level of the cross channel I I through which it might reach the rail sections.

A further advantage of this type of mold is the facility and speed with which the rail ends or other parts to be welded may be preheated by means of the flame of a blow torch or other heating means introduced through the usual preheating gate. The arrangement and disposition of the risers, which act as vents, and of the pouring gate, with its dual connection to the mold space, insures a free flow of the heating medium ,1 around and between the ends of the rails or other parts to be welded, so that the preheating maybe efiected with greater uniformity and the time required for preheating may be considerably curtailed.

Furthermore, welding in accordance with the invention practically eliminates the splashing or 'splattering of the molten metal against the portions of the rails or other bodies to be welded,

which would tend to wash away or materially mar the surfaces of the bodies. Again, inasmuch as the flow of the superheated molten metal through the mold is, in general, in one direction,

produced bythe alumino-thermic process, comprising assembling about the parts to be welded a mold having at least one expansion riser and a pouring gate with an outlet into the lower part of the mold cavity and an inlet substantially above the top of the riser, accurately gauging a charge of alumino thermic material withrespect to the mold cavity and riser to produce only enough molten steel. to satisfactorily complete the weld desired} igniting the charge, pouring the resulting nfolten charge into the mold through the pouring gate, and confining in the pouring gate a suflicient static head of slag to depress the level of metal in the pouring gate below that in the expansion riser.-

2. The method of welding metal parts, such as the ends of rails, by means of superheated steels produced by the alumino-thermic process, comprising assembling about the parts to be welded a mold having at least one expansion riser and a pouring-gate with an outlet into the lower part of the mold cavity and an inletsubstantially above the top of the riser, accurately gauging a As hereinbefore explained, 30

charge of alumino-thermic material with respect to the mold cavity and riser to produce only enough molten steel to satisfactorily complete the weld desired, igniting the charge, pouring the resulting molten charge into the mold through the pouring gate, confining a portion of the slag upon the metal in the pouring gate, and allowing another portion of the slag to overflow over the top of the mold to heat the latter and its contents, said first portion being sufiicient to depress, by its static head, the level on metal in the pouring gate substantially below that in the expansion riser.

' FRANCIS EARLE. 

